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Chemical polishing solution of sintered NdFeB permanent magnet material and processing method

A technology of chemical polishing and permanent magnet materials, which is applied in the field of surface treatment of powder sintered metal materials, can solve the problems of deep grain boundary corrosion, easy residual plating solution, and gaps, etc., to prevent rust and oxidation, uniform corrosion, and grain boundary corrosion Reduced effect

Active Publication Date: 2010-02-03
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

After the aforementioned pre-plating treatment process, the pickling process has the greatest impact on it. After pickling, the Nd-rich phase at the grain boundary is corroded first, and the surface of the NdFeB permanent magnet will leave defects with deep grain boundary corrosion. , and even produce gaps; these grain boundary gaps on the surface of the material are likely to remain in the plating solution during electroplating, chemical plating, etc., which will affect the performance of the subsequent coating layer, such as increasing the porosity of the film layer and the bonding force between the film layer and the substrate. Deterioration, etc., thereby reducing the protective performance of the film layer and limiting the application field of the product

Method used

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  • Chemical polishing solution of sintered NdFeB permanent magnet material and processing method
  • Chemical polishing solution of sintered NdFeB permanent magnet material and processing method
  • Chemical polishing solution of sintered NdFeB permanent magnet material and processing method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] Prepare chemical polishing solution according to the following components:

[0041] Nitric acid 400ml / L

[0042] Phosphoric acid 5ml / L

[0043] Sulfuric acid 5ml / L

[0044] Temperature 25℃

[0045] Take a sintered neodymium iron boron permanent magnet sample and wash it with ultrasonic alkali and ultrasonic water, then immerse the magnet in the above chemical polishing solution, turn it over continuously, the etching time is 10s, then take out the sample and wash it with 1% dilute nitric acid. 30s, ultrasonic washing; 2% trisodium citrate activation for 60s, washing.

[0046] Such as Picture 10 Shown is the micro-topography of the magnet after cleaning with ordinary 3% nitric acid in the prior art, such as Picture 11 Shown is the micro-topography of the magnet after chemical polishing, which is represented by figure 1 with figure 2 It can be seen that the chemically polished permanent magnet samples in this embodiment have more uniform corrosion; figure 1 Shown is a digital p...

Embodiment 2

[0049] Prepare chemical polishing solution according to the following components:

[0050] Nitric acid 400ml / L

[0051] Phosphoric acid 5ml / L

[0052] Sulfuric acid 5ml / L

[0053] Temperature 25℃

[0054] Take a sample of sintered neodymium iron boron and wash it with ultrasonic alkali and ultrasonic water in turn, then immerse the magnet in the above chemical polishing solution, flip once in 1 second, and etch for 30 seconds, then take out the sample and wash it with 1% dilute nitric acid for 30 seconds. , Ultrasonic washing; 4% trisodium citrate activation for 60s, washing.

[0055] The metallographic photo of the magnet after chemical polishing is as follows Figure 5 Shown.

Embodiment 3

[0057] Prepare chemical polishing solution according to the following components:

[0058] Nitric acid 600ml / L

[0059] Phosphoric acid 20ml / L

[0060] Sulfuric acid 20ml / L

[0061] Temperature 55℃

[0062] Take a sample of sintered neodymium iron boron and wash it with ultrasonic alkali and ultrasonic water in turn, then immerse the magnet in the above chemical polishing solution, flip once in 2 seconds, and the etching time is 60 seconds, then take out the sample and wash it with 3% dilute nitric acid for 60 seconds. , Ultrasonic washing; 4% trisodium citrate activation for 120s, washing.

[0063] The metallographic photo of the magnet after chemical polishing is as follows Image 6 Shown.

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Abstract

The invention relates to a chemical polishing solution of a sintered NdFeB permanent magnet material and a processing method. The chemical polishing solution uses water as a solvent and mainly comprises three solutes of nitric acid, phosphoric acid and sulfuric acid. The processing method comprises the following steps: alkaline washing an NdFeB permanent magnet to degrease; dipping the sintered NdFeB permanent magnet into the chemical polishing solution to polish; and then washing and activating the chemically polished NdFeB permanent magnet to complete the whole polishing process, wherein thesintered NdFeB permanent magnet needs to be turned during chemical polishing, and the dipping polishing time of the sintered NdFeB permanent magnet is 10-120s. After the polishing, low-concentrationnitric acid can also be adopted to remove an oxidation film, and alkalescent trisodium citrate which is organic aluminate can be adopted to neutralize surface residual acid. The polishing solution hassimple component and convenient control; and an obtained chemical polishing surface has good glossiness and smooth surface and can be matched with other chemical processing links.

Description

Technical field [0001] The invention relates to a powder sintered metal material surface treatment process, in particular to a sintered neodymium iron boron permanent magnet material surface chemical polishing treatment process. Background technique [0002] At present, the main method to solve the corrosion problem of sintered NdFeB permanent magnets is to deposit a layer of anti-corrosion coating on the surface of the magnet. Electroplating, chemical plating, conversion coating, electrophoresis, physical vapor deposition and other methods can be used to improve its corrosion resistance. Almost all coating methods use alkaline washing and degreasing, pickling and rust removal, and activation. The sintered NdFeB permanent magnet material is a powder alloy formed by pressing and sintering. The low melting point of the neodymium-rich phase forms the only continuous phase of the material, and the neodymium-rich phase is inconsistent with the main phase, and the neodymium-rich phase ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23F3/06
Inventor 宋振纶李建忠应华根杨恒修吴浩杰
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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